1. Field of the Inventive Concepts
The present inventive concepts relate to a method for manufacturing a semiconductor device.
2. Description of the Related Art
Silicon dioxide (SiO2) has been used as a gate dielectric; and as the integration density of semiconductor devices has recently been increasing, the thickness of the gate insulation layer should be continuously scaled down. Silicon dioxide has a low dielectric constant (k) of approximately 3.9, however; consequently, further scaling down of the silicon dioxide gate dielectric layer has become more and more difficult. In addition, thinning the silicon dioxide gate dielectric layer may cause direct tunneling between the semiconductor substrate and the gate electrode. As a result, the leakage current through the reduced-thickness silicon dioxide gate dielectric layer may increase.
Accordingly, recent studies have been directed to using a high-k dielectric layer as a gate dielectric, which is capable of reducing the thickness of the high-k dielectric layer compared to that of a silicon oxide layer used while maintaining the thickness at a level sufficient to prevent direct tunneling. Where the high-k dielectric layer is used as the gate dielectric, however, electron and hole mobility in a channel may decrease as leakage current is generated.